Know your renewables: All about EVs

Electric vehicles are evolving at a rapid pace and look set to displace fossil fuel vehicles in the not-too-distant future. Lance Turner looks at some of the basic concepts and terms you might come across when discussing EVs.

For almost 100 years, the personal automotive industry has been dominated by internal combustion engine (ICE) vehicles, burning either petrol, diesel or LPG. As an alternative to ICE-powered vehicles, electric vehicles (EVs) have been nothing but a novelty to most people, purported to lack range and power, making them unsuitable for most people’s uses.

However, all that is changing, with EVs making steady inroads into the global car market, and even (slowly) here in Australia. The shift in thinking started with the introduction of hybrid electric vehicles (HEVs), such as the Toyota Prius and the Honda Insight. With these vehicles, especially the Prius as it can run in all-electric mode at lower speeds, the general public started to experience some of the advantages of HEVs, such as reduced exhaust pipe emissions, almost silent driving and greatly increased efficiency.

But hybrids have a number of drawbacks. Firstly, as they have both an electric drivetrain and an internal combustion engine, they are more complex than either straight ICE vehicles or EVs. Secondly, although there is an electric drive component to their drivetrains, hybrids still gain all their motive power from fossil fuels (conventional hybrids can’t be charged from the mains grid, and they usually have quite small battery packs), so they are still an unsustainable form of transport, despite having lower emissions than equivalently sized ICE vehicles. The world’s oil reserves will last longer with hybrid vehicles, but will still eventually be exhausted.

As the public’s acceptance of hybrids grew, there was the desire for vehicles that had the advantages of EVs, without the limitations. Hence, the plug-in hybrid electric vehicle (PHEV) was born. These are similar to a hybrid but they differ in two important ways—they have larger battery packs that can be charged directly from mains power, rather than from the on-board ICE, and their electric motor is designed as the primary motor. This means that they can be driven as an EV until the battery is almost flat (or another battery level setpoint), at which time the ICE starts up and provides electricity to charge the battery and power the electric motor.

For owners who do many short trips, PHEVs can run purely on electric power and may never need to use the petrol backup at all. The Holden Volt is an example of such a vehicle, and the most recent incarnation of the Volt has an electric-only range of around 80 km, making it suitable for all-electric use most of the time.

However, there is a need to uncouple personal transport from fossil fuels completely to reduce emissions from this sector, and given that alternative fuels such as ethanol and hydrogen often produce as much CO2 in their production as they save, the only realistic way to achieve this currently is to make cars completely electric, removing the internal combustion engine option altogether.

Read the full article in ReNew 131, covering how an EV works, energy recovery from braking, driving an EV, why buy an EV, battery lifespan, cost and materials, charging and more!